1. Field of the Invention
This invention relates to opto-electronic sensors of the type where the presence of an object is detected by projecting a beam of light through the path of the object and detecting the presence or absence of the light beam, and more specifically relates to power-efficient opto-electronic sensors for detecting the end of a reel of tape in a tape-transport mechanism.
2. Background of the Invention
Opto-electronic sensor means based on the principle of interrupting a light beam are known in the art and have been used in the past to sense the presence of a tape on a tape-transport mechanism. The systems used in the past, however, have been found to consume an excessive amount of power when used in battery-powered portable equipment and particularly where due to design limitations inherent in the transport mechanism the source of light must be placed at a relatively large distance from the light detector, such that a more powerful source of light must be used, consequently requiring a greater amount of current to drive the source of light.